From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8C9F8D33998 for ; Mon, 28 Oct 2024 16:09:55 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1t5SJP-00068R-UG; Mon, 28 Oct 2024 12:09:47 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1t5SJN-00068A-Qb for qemu-devel@nongnu.org; Mon, 28 Oct 2024 12:09:45 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1t5SJM-00064F-48 for qemu-devel@nongnu.org; Mon, 28 Oct 2024 12:09:45 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1730131782; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ea6G5wtzKMhZ2E+87Bpxxtu+p19GIanpiqAsDf/FIog=; b=NNEBN98If8bcWXUYv+SW82BbgjPyNe4Nyo3aU2vr4891W8xOV+KJ21nAWCqRIoEE8KeA1t INVdIj5MimYIDNWsjEKw7KLrYMeFFQwvKbb7a3cHjmfljQ7Uvr1fpm8aqS9PQIJFZzlcm2 1n5SagwyGyafoLfxkpftXjZr3MMNr78= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-53-MFjKr2uwM3GR5URt0I5N1A-1; Mon, 28 Oct 2024 12:09:40 -0400 X-MC-Unique: MFjKr2uwM3GR5URt0I5N1A-1 Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9EE4619560BD; Mon, 28 Oct 2024 16:09:38 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.86]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 2B18619560AA; Mon, 28 Oct 2024 16:09:31 +0000 (UTC) Date: Mon, 28 Oct 2024 16:09:29 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Cornelia Huck Cc: Eric Auger , eric.auger.pro@gmail.com, qemu-devel@nongnu.org, qemu-arm@nongnu.org, kvmarm@lists.linux.dev, peter.maydell@linaro.org, richard.henderson@linaro.org, alex.bennee@linaro.org, maz@kernel.org, oliver.upton@linux.dev, sebott@redhat.com, shameerali.kolothum.thodi@huawei.com, armbru@redhat.com, abologna@redhat.com, jdenemar@redhat.com, shahuang@redhat.com, mark.rutland@arm.com, philmd@linaro.org, pbonzini@redhat.com Subject: Re: [RFC 21/21] arm/cpu-features: Document custom vcpu model Message-ID: References: <20241025101959.601048-1-eric.auger@redhat.com> <20241025101959.601048-22-eric.auger@redhat.com> <0700af51-a1a6-4b11-a4bf-0eaf6e279c6d@redhat.com> <87y128nrfr.fsf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <87y128nrfr.fsf@redhat.com> User-Agent: Mutt/2.2.12 (2023-09-09) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.373, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Mon, Oct 28, 2024 at 05:05:44PM +0100, Cornelia Huck wrote: > On Fri, Oct 25 2024, Daniel P. Berrangé wrote: > > > On Fri, Oct 25, 2024 at 03:28:35PM +0200, Eric Auger wrote: > >> Hi Daniel, > >> > >> On 10/25/24 15:13, Daniel P. Berrangé wrote: > >> > On Fri, Oct 25, 2024 at 12:17:40PM +0200, Eric Auger wrote: > >> >> From: Cornelia Huck > >> >> > >> >> Add some documentation for the custom model. > >> >> > >> >> Signed-off-by: Eric Auger > >> >> Signed-off-by: Cornelia Huck > >> >> --- > >> >> docs/system/arm/cpu-features.rst | 55 +++++++++++++++++++++++++++----- > >> >> 1 file changed, 47 insertions(+), 8 deletions(-) > >> > > >> >> @@ -167,6 +196,16 @@ disabling many SVE vector lengths would be quite verbose, the ``sve`` CPU > >> >> properties have special semantics (see "SVE CPU Property Parsing > >> >> Semantics"). > >> >> > >> >> +The ``custom`` CPU model needs to be configured via individual ID register > >> >> +field properties, for example:: > >> >> + > >> >> + $ qemu-system-aarch64 -M virt -cpu custom,SYSREG_ID_AA64ISAR0_EL1_DP=0x0 > >> >> + > >> >> +This forces ID_AA64ISAR0_EL1 DP field to 0. > >> > What is the "baseline" featureset implied by 'custom' ? > >> there is no baseline at the moment. By default this is a host > >> passthrough model. > > > > Why do we need to create "custom" at all, as opposed to just letting > > users toggle features on "-cpu host" ? > > We could consolidate that to the current "host" model, once we figure > out how to handle the currently already existing properties. Models > based on the different architecture extensions would probably be more > useable in the long run; maybe "custom" has a place for testing. If you can set the features against "host", then any testing could be done with "host" surely, making 'custom' pointless ? With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|